U.S. patent number 4,608,009 [Application Number 06/613,864] was granted by the patent office on 1986-08-26 for thermoforming equipment for differential pressure forming products in thermoplastic material.
This patent grant is currently assigned to John Brown Inc.. Invention is credited to Albert W. Arends, Robert C. Whiteside.
United States Patent |
4,608,009 |
Whiteside , et al. |
August 26, 1986 |
Thermoforming equipment for differential pressure forming products
in thermoplastic material
Abstract
Improvements in differential pressure, thermoforming machinery
for molding articles in thermoplastic material wherein a mold
station incorporates female mold mechanism and opposed mold
mechanism, a web advancing mechanism indexes a plastic web in which
products are to be formed between said mold mechanisms, a drive
moves the female and opposed mold mechanisms between open and
closed positions on opposite sides of the plastic web, severing
knife means is cooperable with a final increment of said relative
movement to dispose said mechanism in closed position to sever the
products formed from the web, and ejector mechanism is operable
after severing is accomplished and there has been relative movement
of said mold mechanisms toward open position to eject the
product.
Inventors: |
Whiteside; Robert C. (Harrison,
MI), Arends; Albert W. (Gladwin, MI) |
Assignee: |
John Brown Inc. (Beaverton,
MI)
|
Family
ID: |
24458976 |
Appl.
No.: |
06/613,864 |
Filed: |
May 23, 1984 |
Current U.S.
Class: |
425/590; 264/153;
264/334; 264/551; 425/292; 425/388; 425/405.1; 425/422; 425/451.6;
425/451.7; 425/592; 425/593 |
Current CPC
Class: |
B29C
51/18 (20130101); B29C 51/44 (20130101); B29C
51/32 (20130101) |
Current International
Class: |
B29C
51/18 (20060101); B29C 51/44 (20060101); B29C
51/32 (20060101); B29C 51/26 (20060101); B29C
51/30 (20060101); B29C 051/36 (); B29C
051/44 () |
Field of
Search: |
;425/145,161,162,292,324.1,327,347,388,395,397,45R,422,451,451.2,451.5,451.6
;264/153,334,549-551,553 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Woo; Jay H.
Assistant Examiner: Heitbrink; Timothy W.
Attorney, Agent or Firm: Learman & McCulloch
Claims
What is claimed is:
1. A differential pressure, thermoforming machine for molding
articles in thermoplastic material comprising:
a. a frame;
b. a mold station incorporated in said frame, said mold station
including a female mold mechanism with cavity forming means and an
opposed mold mechanism;
c. a longitudinally extending, web advancing mechanism for indexing
a plastic web, in which products are to be formed, between said
mold mechanisms;
d. means for relatively moving said female and opposed mold
mechanisms between mold open and mold closed positions on opposite
sides of said plastic web;
e. a roll stand upstream from said mold station for supporting a
roll of the plastic web in a position aligned longitudinally with
said mold station such that a supply of the web can be unwound from
the roll and fed to the web advancing mechanism;
f. heater elements disposed between the roll stand and mold station
for heating the web to a moldable state;
g. a dancer arm assembly movable in an oscillating path angularly
to the longitudinal extent of said advancing mechanism and said web
to pull a section of said web from the roll such as to form a loop
of predetermined extent and then release it for movement in indexed
increments to the mold station;
h. means mounting said dancer arm assembly for swinging movement
about a generally horizontal axis extending transversely to the
web;
i. a crank link having a first end connected to the dancer arm
assembly for moving said dancer arm assembly in an oscillating
path;
j. a drive crank pivotally connected to said link oscillatable
through substantially half an arc of revolution for moving said
crank link through part of a revolution wherein said crank link
drives said dancer arm assembly first at a gradually accelerating
speed, then at increased speed, and finally at a gradually
decelerating speed, when said dancer arm assembly is moved both in
a direction to release the web to the advancing mechanism and then
away from the web to pull a further increment of web from the roll;
and
k. drive means for moving said drive crank in correlation with said
web advancing mechanism.
2. The machine of claim 1 wherein said drive means for moving said
drive crank comprises a spur gear, at least one rack in mesh
engagement, with said spur gear, and separate power cylinders
powering said rack in correlation with said web advancing mechanism
to revolve said gear first in one direction of rotation when the
advancing mechanism is operating, and then in a return
direction.
3. A differential pressure, thermoforming machine for molding
articles in thermoplastic material comprising:
a. a frame;
b. a mold station incorporated in said frame, said mold station
including a female mold mechanism with cavity forming means and an
opposed mold mechanism;
c. a longitudinally extending, web advancing mechanism for indexing
a plastic web in which products are to be formed between said mold
mmechanisms;
d. means for relatively moving said female and said opposed mold
mechanisms between open and closed positions on opposite sides of
said plastic web;
e. severing knife means around said cavity forming means cooperable
with a final increment of said relative movement to dispose said
mechanism in a closed position to sever the products formed from
the web;
f. said means for relatively moving said mold mechanisms including
a drive gear for causing relative movement to dispose said mold
mechanisms in a forming position, and a final most-closed position
in which severing of the articles by said severing knife means is
accomplished;
g. a ejector pin mechanism operable after severing is accomplished
and there has been relative movement of said mold mechanisms toward
open position to eject the product from the cavity forming means;
and
h. pusher means connected to be operated by said relative movement
of one of said mold mechanisms to push the ejected product in a
direction to clear the mold station.
4. A thermoforming machine for molding articles in thermoplastic
material comprising:
a. a frame;
b. a mold station incorporated in said frame, said mold station
including a mold assembly comprising a female mold mechanism with
cavity forming means, and an opposed mold mechanism;
c. a web advancing mechanism for disposing a plastic web, in which
products are to be formed, between said mold mechanisms;
d. means for relatively moving said female and said opposed mold
mechanisms between open and closed positions on opposite sides of
said plastic web;
e. said means for relatively moving said female and said opposed
mold mechanisms including expandible and contractible toggle links
connected between said frame and one of said mold mechanisms, and
drive means incorporating a motion transfer mechanism for
relatively expanding and contracting said toggle links operable to
expand said toggle links and move said one mold mechanism toward
the other mold mechanism to a first forming position, and then to
expand said toggle links a final increment to move said one mold
mechanism a final increment toward the other mold mechanism to a
severing position;
f. severing knife means carried by said mold assembly around said
cavity forming means cooperable with said final increment of
expansion to sever the products formed from the web;
g. said motion transfer mechanism including relatively
repositionable, toggle link expanding, coupled parts operative in
one relative position to transfer the motion of said drive means to
cause expansion of said toggle links to move said one mold
mechanism to said first forming position and then to cause further
expansion of said toggle links to move said one mold mechanism to
said severing position; said repositionable toggle link expanding,
coupled parts being operative in a second relative position to move
said one mold mechanism to said first forming position and to
disable the said further expansion of said toggle links necessary
to reach severing position; and
h. position changing mechanism actuable for repositioning said
parts between said first and second relative positions.
5. The machine of claim 4 wherein said drive means is controlled to
drive said motion transfer mechanism through a continuous cycle
commencing with said expansion of said toggle links a final
increment to move said one mold mechanism to severing position,
thence proceeding with contraction of said toggle links to move
said one mold mechanism to a position removed from said other mold
mechanism to permit operation of said web advancing mechanism, and
terminating in expansion of said toggle links to move said one mold
mechanism to said first forming position.
6. The machine of claim 4 wherein an ejector pin mechanism is
mounted by said mold mechanism and operable, after severing and
movement of said one mold mechanism away from said other mold
mechanism, to eject the product from the cavity forming means; and
pusher means is connected to be operated by said movement of said
one mold mechanism to push the severed and ejected product in a
direction to clear the mold station.
7. The machine of claim 4 wherein said position changing mechanism
comprises a power cylinder carried by one of said repositionable
parts and connected to the other.
8. The machine of claim 4 wherein said toggle links are revolvably
coupled by a coupling pin and said parts include a connecting rod
connected to said coupling pin and driven in a path to push said
toggle link connecting pin to expand and contract said links.
9. The machine of claim 4 wherein said repositionable toggle link
expanding coupled parts include a revolvable pin connecting said
toggle links which includes an eccentric portion rotatably received
by one of said toggle links such that revolving movement of said
eccentric portion in one direction causes said further expansion of
said toggle links, and a connecting rod coupled with said eccentric
portion and to said drive means.
10. The machine of claim 9 wherein said connecting rod is driven in
a path to push said pin bodily in a direction to contract and
expand said toggle links, and also to revolve said pin.
11. The machine of claim 10 wherein said position changing
mechanism includes a power cylinder connected between said
revolvable pin and connecting rod to alter the motion transfer of
said revolvable pin and said connecting rod by relatively pivoting
said revolvable pin in the opposite direction.
12. A thermoforming machine for molding articles in thermoplastic
material comprising:
a. a frame;
b. a mold station incorporated in said frame, said mold station
including a mold assembly comprising a female mold mechanism with
cavity forming means, and an opposed mold mechanism;
c. a mechanism for disposing a plastic web, in which products are
to be formed, between said mold mechanisms;
d. means for relatively moving said female and said opposed mold
mechanisms between open and closed positions on opposite sides of
said plastic web;
e. said means for relatively moving said female and said opposed
mold mechanisms including expandible and contractible, pivotally
coupled toggle links connected between said frame and one of said
mold mechanisms, and drive means incorporating a motion transfer
mechanism for relatively expanding and contracting said toggle
links operable to expand said toggle links and move said one mold
mechanism toward the other mold mechanism to a first forming
position, and then to expand said toggle links a final increment to
move said one mold mechanism a final increment toward the other
mold mechanism to severing position;
f. severing knife means carried by said mold assembly around said
cavity forming means cooperable with said final increment of
expansion to sever the products formed from the web;
g. said motion transfer mechanism including a revolvable pin
connecting said toggle links which includes an eccentric portion
rotatably received by one of said coupled toggle links such that
revolving movement of said eccentric portion in one direction
causes further expansion of said toggle links, coupled with a
connecting rod connected with said drive means to transfer the
motion of said drive means to first cause expansion of said toggle
links to move said one mold mechanism to said first forming
position and then to cause further expansion of said toggle links
to move said one mold mechanism to said severing position via
rotation of said pin.
13. The improved invention of claim 12 wherein said drive means
comprises a crank arm connected to one end of said connecting rod
and moving it in a path to push said pin bodily in a direction to
contract and expand said links, and to also revolve said pin.
Description
BACKGROUND OF THE INVENTION
The thermoforming art is well developed and normally such machinery
includes mold carrying platens driven cyclically in relative
movement toward and away from each other between open and closed
positions to thermoform plastic parts on a mass production basis.
Various machines have been proposed to satisfy various of the
requirements for efficient and reliable thermoforming machines, and
among them are machines incorporating some of the features
disclosed in the following U.S. Pat. Nos.:
U.S. Pat. Nos. 3,105,270; 3,726,458; 3,216,491; 3,876,488;
3,338,997; 4,354,816; 3,346,923; 4,368,024; 3,577,596; 3,890,308;
3,719,445; 4,158,539.
Improvements in such systems have been generally concerned with
efforts to increase the productivity of such machinery and to
operate it at ever-faster speeds to turn out products at an
ever-increasing pace. Much of the machinery which is in use is of a
relatively heavy and complex nature and a need has been identified
for smaller thermoforming systems which are, for instance, capable
of the "trim-in-place" processing of polypropylene and other
thermoplastic materials. A thermoformer of this type may, for
example, provide a maximum mold size of 20.times.13 inches with a 5
inch depth of draw. Such a machine will handle 22 inches.times.30
inch diameter rolls of material in thicknesses up to 2 mm., at
operating speeds of as much as 40 strokes per minute.
SUMMARY OF THE INVENTION
Systems of the type which we have designed require that the
material be efficiently and reliably pulled from the supply roll
and advanced between the molds at speeds consonant with the mold
cycles utilized. Such systems further require drive mechanism for
moving the molds relatively to provide a "trim-in-place" feature,
and to do so conjunctively with a "no-trim" mechanism which will
effectively disable the trim movement on a selective basis. Such
systems also require mechanism for synchronously removing the
products which are separated from the web from between the molds to
a collection station in an advantageous and reliable manner.
Finally, systems of this type must provide other operating
advantages which enhance the saleability of such machines in
various countries throughout the world.
One of the prime objects of the present invention is to design a
relatively smaller and yet efficient machine which is still capable
of producing parts at relatively high speeds in a manner which
enhances the productivity, performance and profitability of such
machinery.
Still another object of the invention is to provide an extremely
versatile machine of relatively inexpensive construction which is
well suited to the world market for such machines.
Still another object of the invention is to provide dancer
mechanism for thermoforming equipment which is not subject to the
extremes of acceleration and deceleration which were a
characteristic of prior designed machinery, and which, accordingly,
avoids the problems previously encountered as a result.
A further object of the invention is to provide dancer roll drive
mechanism which operates efficiently and smoothly, avoids tearing
of the thermoplastic sheet and undue jarring and the consequent
wear of the machine parts, and does so without sacrificing cycle
time.
Still another object of the invention is to provide very efficient
drive mechanism for moving at least one of the mold members
relative to the other which provides a part "trim-in-place" feature
while still permitting an effective "no-trim" control which
provides for the optional and selective disablement of the
"trim-in-place" increment of travel.
Still another object of the invention is to design simple and
effective product ejecting mechanism operated via the movement of
at least one of the molds to a spread, moldopen position to move
parts trimmed from the web and ejected from the mold cavities, over
to a collection station.
Other objects and advantages of the invention will become apparent
by reference to the following specification and to the
drawings.
IN THE DRAWINGS
FIG. 1 is a schematic, side elevational view of a thermoforming
system employing the improvements of the invention;
FIG. 2 is a greatly enlarged, fragmentary view showing a dancer
roll in several positions, the chain lines indicating the extended
position of the dancer roll in which the roll operates to pull a
length of material from the plastic roll preparatory to feeding it
between the ovens in increments to a position between the
thermoforming molds;
FIG. 3 is a fragmentary, front elevational view thereof;
FIG. 4 is a considerably enlarged, fragmentary transverse
elevational view illustrating the drive link mechanism for moving
the lower mold platen upwardly and downwardly;
FIG. 5 is a side elevational view thereof;
FIG. 6 is a still more enlarged, sectional elevational view,
particularly illustrating "trim-in-place" knives which may be used
with the machinery;
FIG. 7 is a fragmentary, end elevational view, particularly
illustrating the ejector members for moving the trimmed products
out of the mold cavities;
FIG. 8 is a schematic side elevational view thereof;
FIG. 9 is a fragmentary, schematic side elevational view
illustrating pusher mechanism linkage for removing the trimmed
parts in an advanced position;
FIG. 10 is a view similar to FIG. 9, but showing the part
displacing pusher moved to fully displaced position between the
upper and lower molds to push the parts ejected from the mold
cavities over to a part collecting conveyor;
FIG. 11 is a fragmentary, top plan view of a portion of the pusher
plate; and
FIG. 12 is a typical electrical control diagram.
THE GENERAL MACHINE
Referring now more particularly to the accompanying drawings, and
in the first instance to FIG. 1, thermoplastic materials such as
polypropylene, polyethylene, and polystyrene are supplied in the
form of a wound roll, generally designated R, which in the usual
manner is supported for rotation on supports 11a on shaft 11,
which, in the usual manner, is journaled in bearings 11b (see FIG.
2) supported on the machine frame F. The machine frame is shown
only fragmentarily as comprising end and side rails 8 and 9
respectively, supported on legs 12.
The plastic web or sheet P is shown in FIG. 2, in chain lines, as
having been pulled from the roll R by a dancer roll 13, mounted on
arms 14 which are pivotally supported by a shaft 15 which is
journaled in bearings 16 on frame legs 12. The dancer roll assembly
will presently be described in more detail.
The plastic web P leads around under the dancer roll 13, and up
over roll supports 18. As is usual, and described in the present
assignees' U.S. Pat. No. 3,216,491, which is incorporated herein by
reference, advancing chains 19 provided with piercing pins 20 at
each side of the machine, then engage the edges of the plastic web
P, and pierce them to grip the web and enable the chains to move
the sheet in indexing increments.
The chains 19, which receive the web from a bridging web support
pan 17, may be trained around sprockets 21 mounted on shaft 21a,
side rails 21b and downstream sprockets 22 mounted on an idler
shaft 23. The chains 19 also train around sprockets 24, mounted on
an idler shaft 25, and chain drive sprockets 26 mounted on the
chain drive shaft 27 which is powered by suitable Geneva mechanism
or the like, to move the chains 20 in advancing increments in the
conventional manner. The drive shaft 27 is driven synchronously
with the mold platen closing and opening drive mechanism to advance
the next increment of plastic web P between the molds of the
thermoforming machine when the molds are in spread position.
Provided in the usual manner to heat the thermoplastic web P to a
deformable condition are temperature controlled upper and lower
ceramic heater ovens 28 and 29, respectively, situated between the
dancer roll 13 and the upper and lower mold assemblies generally
designated M-1 and M-2 respectively, generally. As will become
apparent when the mold station elements are described in more
detail, the upper mold assembly M-1 is stationary and it is the
lower mold assembly M-2 which is moved upwardly and downwardly with
respect to it.
THE DANCER MECHANISM
As FIGS. 2 and 3 particularly indicate, the dancer roll support
arms 14 are fixed at their front ends to a shaft 15 and the roll 13
is oscillated in the arcuate path indicated in FIG. 2 by a
connecting rod 31. At its lower end, rod 31 is pivotally connected
as by pin 32 to a forwardly extending link 33 which is fixed to
shaft 15. At its upper end, connecting rod 31 is connected via a
pivot pin 34 with a vertically extending drive member or crank 35,
which is swung through a 180.degree. arc, and then back again. The
drive crank 35 is fixed to a drive shaft 36 on which a spur gear 37
is keyed. Provided to drive the gear 37 first in one direction of
rotation and then in the other is a rack gear 38. The rack gear 38
is driven in opposite directions by opposed fluid pressure operated
cylinders 39 and 40 having floating pistons provided in opposed
relation. When air is admitted to the ends of cylinder 39 to drive
the rack 38 to the left in FIG. 2, air must be egressed from the
far end of the cylinder 40 to permit this to happen, and vice versa
when rack 38 is returned. A bracket 41 may be provided for
supporting the cylinders 39 and 40 from frame rails 9.
As will be apparent from FIG. 2, the support arms 14, which have
brackets 14a journaling the dancer roll shaft 13a, move through
about 25.degree. of travel and then swing back. What is achieved is
a relatively rapid payout of material from the roll R, then a rapid
movement of dancer roll 13 upwardly so that the chains 20 can
synchronously index the web. The roll 13 moves with such speed that
the material can index without delay and the indexing is completed
when roll 13 reaches the "up" position.
Previous mechanism employing air cylinders to directly power the
dancer roll support arms created problems because of the
acceleration and deceleration extremes. Now, with crank 35 swinging
180.degree., and operating through connecting rod 31, a controlled
acceleration and deceleration is built in and the shock effects of
acceleration and deceleration are much mitigated.
THE MOLD STATION
As FIG. 1 indicates, the upper mold assembly M-1 is stationary and
includes a mold member 45 supported on frame F opposite the mold
assembly M-2 which includes the usual mold member 46, with a series
of mold cavities 47. The upper mold assembly M-1 has openings 48
for the plug assist members 49, which, as FIG. 4 indicates, are
movable down into mold cavities 47 to assist in moving portions of
the plastic web P into the cavities. The plug assists 49 may be
mounted on rods 49a, attaching to a support plate 50 which is
connected to the piston rod 51 of an airoperated cylinder 52,
housing a piston 53. Supports 45a may be provided for supporting
the cylinder 52 on mold member 45. Cylinder 52 is a double-acting
cylinder, which has its piston rod 51 extending from both ends, and
the upper end of rod 51 mounts a stop plate 54, which is movable
down into engagement with the frame supported stop 55.
It is to be understood that the plug assists 49 operated in
conjunction with an air pressure supplying valve and manifold
device 56, which, after the plug assists 49 have moved the plastic
P into the cavities 47, provides the air pressure to intimately
engage the plastic with the contours of the mold cavities. Vacuum
ports 46a can also be provided in the mold 46 in the usual manner.
As FIG. 4 indicates, the lower end of each mold cavity 47 is formed
by an ejector pin assembly, generally designated 57, which includes
ejector pins 58, to presently be described with respect to their
operation in more detail, and ejector pin heads 59 which provide
the desired configuration for the bottom of the mold cavities
47.
As shown more particularly in FIG. 6, a steel ring die 61 may be
fixed in position by the mold 46 to form the upper end of each mold
cavity 47. As FIG. 6 indicates, each ring 61 is a severing or
cut-off knife which is effective to sever the cup-shaped part C
which has been formed in the molding operation from the plastic web
P.
Provided on frame support members 62, at the mold station, are a
pair of ways or guides 63 on which a platen 64 (which carries mold
46) is guided during raising and lowering movement. Supporting
plates 65 are provided on the ends of platen 64 for the purpose of
mounting bearing blocks or gibs 66 and 67 which travel along the
ways 63.
The platen 64 is raised and lowered by toggle linkage assemblies
generally designated 70, which are of a unique nature to provide
for both a final upward incremental movement of mold 46 and
severing rings 61, and for a selectively operated, "no-trim"
repositioning operation. The toggle linkage is driven in a scissors
fashion to expand and retract, and thereby move the platen 64 and
mold 46 upwardly and downwardly in the thermoforming cycle.
Each toggle link assembly 70 is connected to the platen 64 by a bar
71, and is connected to the frame F at its lower end by a pin 73
supported by a pair of frame support brackets 72. The toggle links
74 of each assembly 70 are pivotally mounted on a frame-fixed pin
73 and, at their upper ends, each pair of links 74 is provided with
co-axial bores 75 which support the co-axial ends of a pin 76
having an enlarged eccentric central part 77 (FIG. 5). The ends of
pin 76 have an axis a and the portion 77 has an axis b. The upper
toggle links 77a for each assembly 70 are each connected to the
platen 64 by a pivot pin 78a carried by the bars 71, and at their
lower ends have bores 77b which journal the eccentric portions 77.
Keyed to each portion 77 as at 77c is a block 78 on one end of
which a connecting rod 79 is pivoted, as by a pin 79a. The
connecting rod 79 for each assembly 70 is driven by a crank arm 80
mounted on a drive shaft 81 for moving the crank arms 80 through
360.degree. increments of rotation.
Projecting from each block 78 are braces 82 for pivotally mounting
a spring returned, single-acting cylinder 83, as with a pin 84. The
piston rod 85 of each cylinder 83, is pinned as at 86 to connecting
rod 79. As will later become apparent, cylinders 83 may be push
button operated by the machine operator to bring a "no-trim"
repositioning into play.
The purpose of eccentric pins 76 is to provide a final increment of
upward movement of mold 46 via eccentric portions 77 at the
beginning of the mold retract cycle, after a short time delay to
permit cooling of the parts C which are formed. Drive shaft 81 may
be driven via a suitable electric motor M through suitable Geneva
mechanism or the like (not shown), such that crank arms 80 are
indexed in a manner which later will be described.
THE PART EJECTING MECHANISM
FIGS. 7-10 schematically depict the mechanism for, first of all,
moving the parts C upwardly out of the mold cavities 47 and, then,
pushing them laterally to a position removed from between the mold
assemblies M-1 and M-2. For the purposes of convenience of
illustration, the mold 46 has been shown as only of sufficient
width to produce a single row of cups C in these Figures. In FIGS.
7 and 8 the ejector pins 58 are shown as connected by a plate 90.
The plate 90 mounts receiving guide rods 91 which pass through
openings in the plate 92 (which is attached to the frame F). Coil
springs 93 are provided around the pins 91 to restrain the plate 90
and ejector pins 58 when the platen 64 moves downwardly.
The upper ends of springs 93 are normally disposed a predesignated
distance below the plate 90, as shown in FIG. 7. When mold 46
initially lowers, the ejector pin assembly 57 will lower with it
for a sufficient portion of the mold's travel to clear the sag in
the sheet. Then, when plate 90 contacts springs 93, mold 46 will
continue to lower, while the springs 93 maintain the heads 59 of
the pin assemblies in position such that the parts C are soon
positioned above the mold cavities 47 and die rings 61.
In FIG. 9, mechanism is disclosed for moving such cups C out from
between the mold assemblies M-1 and M-2. Provided at each side of
the machine, downstream from the mold assemblies M-1 and M-2, are a
pair of guide rods 94 which mount pusher plate carriages 95 to
which a pusher plate 95a is connected. Brackets 96 on the frame F
are provided at each side of the machine to support pivotal links
97 via pivot pins 98. Each arcuately oscillating link 97 is
connected with a carriage 95 via a link 99, and pivot pins 100 and
101. Each link 97 is connected with the platen 64 via a link 102,
and pivot pins 103 and 104.
The linkage is uniquely designed so that initial downward movement
of the platen 64 creates no substantial forward movement of the
pusher plate 95a. It is only when link 102 travels from the
position shown in FIG. 8 to the position shown in broken lines at x
in FIG. 9, that material forward movement of plate 95a commences.
The built-in time delay provides sufficient time for the cups C to
clear the cavities 47 and rings 61 before pusher plate 95a is moved
across.
In the advanced position of the pusher plate 95a, which is reached
automatically when the platen 64 is lowered to the position shown
in FIG. 10, the parts or cups C are engaged by the pusher 95a and
moved over to a collection station which may comprise, for example,
a transversely moving belt conveyor 105. FIG. 11 discloses the
configuration of the plate 95a which normally is provided with
cupreceiving recesses 95b.
THE OPERATION
Assuming that the mold assembly M-2 is stopped in raised forming
position with the crank arms 80 in the 10 o'clock position shown in
FIG. 5, the next successive cycle will be initiated by a resetting
timer T which, after a time delay sufficient to provide for some
cooling of the formed parts C to be trimmed, engages clutch CL
(connected with constantly driven motor M) to drive shaft 81. Crank
arms 80 will commence to move toward the 12 o'clock position, but
because the movement is initially mostly upwardly rather than to
the right in FIG. 5, the effect is to raise the position of pin 80
and the right end of block 78 without contracting links 74, 77a.
The effect is to rotate eccentric portion 77 slightly
counterclockwisely in FIG. 5 with respect to pin axis "a" and raise
links 77a upwardly. This moves platen 64, mold 46 and severing dies
upwardly sufficiently to trim the parts (see FIG. 6). Further
movement of the arms 80 toward the 12 o'clock position provides
much more rightward than upward movement and this starts to
collapse the links 74, 77a and lower mold 46. At this time,
contacts 106 close to energize the clutch CL-1, which drives the
shaft 27, powering the web advancing chains 19. At the same time,
dancer roll 13 is operated by the arm 35 moving 180.degree. from
the down position in which it is shown in FIG. 3, to an up position
and, in so doing, moving the dancer roll 13 from the "at rest"
broken line position shown in FIG. 2, to the solid line position.
This occurs when double acting, solenoid operated cylinders 39 and
40 are operated by contacts 107 controlled by an encoder such as
shown in U.S. Pat. No. 3,814,934 or the like, which is responsible
for closing and opening the various sets of contacts which operate
the various components of the machine. Contacts 108 are then
immediately closed by the encoder to operate cylinders 39 and 40 in
the reverse direction and move roll 13 back to the down
position.
During operation of the chains 19 and roll 13, as crank arms 80
move right and toward the 4 o'clock position, the links 74 and 77a
will be collapsed to lower the mold 46 and platen 64. After an
initial lowering movement, the plate 90 engages the springs 93 and
holds the cups C in position, while the platen 64 and mold 46
continue to descend. At the same time, movement of the platen 64
downwardly causes the linkage 102, 97 and 99 to react to initially
delay, as previously explained, and then to move the pusher
carriage mounts 95 forwardly and cause the pusher plate 95a to push
cups C over to a discharge conveyor 105. On the later movement of
mold 46 upwardly, the pusher plate 95a is automatically removed
from between the mold assemblies M-1 and M-2 to the FIG. 9 position
by the same linkage 102, 97 and 99.
During the return movement of roll 13, a fresh length of plastic
web P is pulled from the roll R and the dancer roll 13 is then
halted in down position. The advancing chains 19 have finished
their sheet forwarding movement and shaft 27 is halted at the time
roll 13 commences to move downwardly. At this time, crank arms 80
are in the 7 o'clock position and the mold 46 (which reached down
position when crank arms 80 were in the 4 o'clock position) has
moved upwardly, to a considerable extent, the links 74 and 77a
expanding as the crank arms 80 moved leftward. When the crank arms
80 reach the 10 o'clock position where the links 74, 77a are fully
expanded, drive shaft 81 is braked and halted.
At this time, the mold 46 has been raised to a position of
substantial engagement with the plastic web P and contacts 109 are
made to operate cylinder 52 and cause the plug assists 49 to move
areas of the heated deformable plastic into the mold cavities 47.
At about the time plug assists 49 reach their lowermost positions,
contacts 110 are made and the air valve 56 operates to release air
under pressure to passages 48 to complete moving the deformable
plastic web portions into intimate engagement with the contours of
the mold cavities 47. Contacts 109a are then made by the encoder to
move cylinder 52 and piston rod 51 upwardly and raise the plug
assists 49. The crank arms 80 remain at rest in the 10 o'clock
position until the next cycle is commenced. Because the mold
closing and opening motion is crank-operated, via cranks 80, the
acceleration and deceleration is gradual, and the problems incident
to sudden starts and stops do not occur. The machine is accordingly
considerably more trouble-free than much of the prior art
machinery.
In the set-up of the machine, and until all of the various parts
are aligned and the operation is "proved", it is often desirable to
eliminate the severing in place operation, such that the entire web
with the cups formed therein proceeds to the scrap grinder. The
operator need merely press a push button 111 which operates each
cylinder 83 and retracts the piston rod 85 of each. Since crank
arms 80 cannot move, this retraction causes each block 78 and
eccentric pin portion 77 to swing downwardly (clockwisely in FIG.
5) about an axis "a" and lowers the links 77a just sufficiently so
that movement of the crank arms 80 away from the 10 o'clock
position toward the 12 o'clock position will not cause sufficient
upward movement of the mold 46 and severing rings 61 to sever the
parts formed. The position of links 74 does not change when the
position of eccentric portion 77 is changed. When the operator
desires to again include the trim-in-place feature, it is only
necessary to release push button 111 and permit the single acting
cylinders 83 to return to the FIG. 5 position.
While one embodiment of the invention has been described in detail,
it will be apparent to those skilled in the art the disclosed
embodiment may be modified. Therefore, the foregoing description is
to be considered exemplary, rather than limiting, and the true
scope of the invention is that defined in the following claims.
* * * * *